What Is CPA (Cost Per Acquisition)? Formula and Benchmarks
CPA (Cost Per Acquisition) is ad spend divided by the number of conversions — the cost to acquire one result. Here's the formula, what a good CPA looks like, and how CPA differs from CAC.
CPA (Cost Per Acquisition) is your ad spend divided by the number of conversions — the cost to acquire one result, whether that's a sale, a lead or a signup. It answers a blunt question: how much did each outcome cost us?
The CPA formula
CPA = Ad spend ÷ Number of conversions
Example: a campaign spends $1,200 and produces 40 purchases. CPA = 1,200 ÷ 40 = $30 per acquisition. Define clearly what counts as a conversion — mixing leads and sales in one CPA makes the number meaningless.
What is a good CPA?
A good CPA is any CPA below your maximum profitable acquisition cost. Work it out from your economics:
- Ecommerce: maximum CPA ≈ average order value × profit margin (before you factor in repeat purchases).
- Lead gen: maximum CPA ≈ lead value × close rate, where lead value is the profit from a won deal.
- Subscription: you can often pay more than first-month revenue because payback happens over the lifetime.
CPA vs CAC
CPA usually refers to the cost of a single conversion event inside an ad platform. CAC (Customer Acquisition Cost) is broader: total sales and marketing cost divided by new customers won, including salaries, tools and discounts. CPA is a campaign metric; CAC is a business metric — don't use them interchangeably.
Common CPA mistakes
- Counting platform-reported conversions that are double-counted or unverified.
- Comparing CPA across currencies or across different conversion definitions.
- Judging CPA before conversions have matured (conversion lag inflates recent CPA).
- Cutting a campaign on CPA alone while ignoring lifetime value.
How Floowzy helps
Floowzy calculates CPA per campaign and per platform in a single currency from your real conversion data, tracks it period-over-period, and flags spend that produces no conversions — so a rising CPA is caught while you can still act on it.
Frequently asked questions
- Is a lower CPA always better?
- Not always. A very low CPA can come with low volume or low-quality conversions. Read CPA next to volume and to the value of each conversion — a slightly higher CPA that brings far more profitable customers can be the better outcome.
- What's the difference between CPA and CPL?
- CPL (Cost Per Lead) is a specific kind of CPA where the conversion is a lead rather than a sale. CPA is the general term for the cost of any defined conversion.
- How do I lower my CPA?
- Improve conversion rate (offer, landing page, creative), tighten targeting, cut spend on non-converting placements, and refresh tired creative before fatigue pushes costs up. Fixing tracking so you don't undercount conversions often lowers reported CPA too.